Assembling Ti3C2MXene on a S‐Scheme Heterojunction with Oxidative Covalent Organic Frameworks for Photocatalytic Hydrogen Evolution

Photocatalytic evolution of hydrogen is a very promising and sustainable technology. However, studying multiple composite systems that include oxidized covalent organic frameworks (COFs) for the purpose of photocatalytic hydrogen production poses a significant challenge. This challenge arises from the rapid charge recombination introduced by individual photocatalysts, as well as the limited availability of oxidative COFs. Herein, ZnIn 2 S 4 (ZIS)–COF (TPN‐COF) S‐scheme heterojunction loaded with Ti 3 C 2 MXene (MX) is rationally designed for efficient photocatalytic H 2 evolution. The best‐performing sample, MX/TPN‐COF@ZIS (with a ZIS:TPN‐COF mass ratio of 3:2, with 2% MX), reaches an H 2 production rate of 4.01 mmol g −1 h −1 under visible light irradiation. Experimental and theoretical investigation reveals that the formation of S‐scheme heterojunctions between ZIS and COF can achieve the transfer of the electrons from COF to ZIS driven via the in‐built electric field while allowing the migration of electrons from ZIS to MX. Furthermore, multiple in‐built electric fields not only stimulate effective separation and migration of charges, but also inhibit recombination of carriers in a single semiconductor. This triple‐coupled photocatalytic system serves as a practical guideline for promoting the development of hydrogen.